The present invention relates to a power control device for controlling the amount of power to be consumed in a processor.
Computers, microprocessors, microcontrollers, digital signal processors (DSPs), etc., are known in the art. Herein, these stored program type devices are referred to generally as xe2x80x9cprocessorsxe2x80x9d.
Some conventional processors include a power control device. For example, a power control device for a processor lowers the frequency of the internal clock of the processor to a lower frequency in the stand-by mode, thereby reducing the power consumption.
With the conventional power control device for a processor, however, the lower clock frequency cannot be determined by the user of the processor. Moreover, the stand-by mode is selected through execution of a special instruction by the processor, thereby increasing the size of the program.
An object of the present invention is to allow the user to finely define the low power mode operation of a processor.
Another object of the present invention is to provide a power control device of an event-driven type, thereby reducing the programming load.
In order to achieve these objects, the present invention provides a power control device for controlling the amount of power to be consumed in a processor, the power control device including: a power table including a plurality of power control registers each rewritably storing power control information; a condition determiner for rewritably storing a plurality of operating conditions and determining which one of the plurality of operating conditions is satisfied by a current operation of the processor so as to supply an index signal to select one of the plurality of power control registers based on the determination; and a controller for controlling the power consumption in the processor according to the power control information in one of the power control registers that is selected by the index signal.
With the power control device of the present invention, the user is allowed to rewrite the power control information and the operating conditions before or while the program is executed so as to finely define the low power mode operation of the processor. The rewrite operation can be done when the processor is manufactured.
In the power control device of the present invention, the current condition of the processor is automatically determined by the condition determiner. Therefore, it is possible to realize an event-driven type power control device by using, as an input to the condition determiner, an address indicated by the program counter of the processor, the type of an event that has occurred in the processor, the time indicated by the time signal from the processor, etc.